The present invention relates generally to a method and a device for restarting a spinning operation in work stations of an open-end spinning machine after replacement of a cheese with an empty cheese tube, and relates more particularly to such a method and device wherein the work stations each comprise a spinning device for producing a yarn and a winding device with a creel for winding the yarn into a cheese and wherein an automatically operating service unit comprising an auxiliary yarn supply device attends the plural work stations.
As is known, open-end spinning machines have a plurality of adjacent work stations, each of which comprises a spinning device for manufacturing a yarn and comprises a winding device with a creel and a yarn traversing device for producing a cross-wound bobbin commonly referred to as a cheese.
The work stations of such open-end spinning machines are typically served by automatically operating service units that intervene if a need for service has occurred at one of the work stations. Such a need for service occurs, e.g., in case of a yarn break or if the cheese at one of the work stations has attained its prescribed diameter and must be replaced by a new empty tube.
That is, such service units described, e.g., in German Patent Publication DE 44 43 818 A1 or in DE 43 13 523 A1 not only eliminate yarn breaks but also automatically carry out cheese/empty tube replacements. For example, in the case of a cheese/empty tube replacement, the full cheese is removed from the creel of the particular work station and transferred onto a transport device of the machine. Then, a new, empty tube is placed into the creel, the open-end spinning device started to spin again by means of a so-called auxiliary yarn and the new spinning yarn is fixed on the freshly replaced empty tube.
The known service units comprise numerous manipulation devices, e.g., a pivotably supported, vacuum-loadable suction nozzle for grasping a trailing yarn wound onto the cheese in the case of a yarn break, and a supply device with a pivotably supported supply tube for making available an auxiliary yarn required after a cheese/empty tube replacement for a spinning restart. Moreover, these service units comprise a yarn placement device for fixing the new spinning yarn on the empty tube and for creating a yarn reserve winding.
The described service units have proven themselves in practice and have been used for years with success. However, such service units have the disadvantage that they require a vacuum, e.g., for operating their suction nozzle and to remove by suction and dispose of any auxiliary yarn or the spinning start yarn portion.
The known open-end spinning machines are provided for this reason with so-called suction traverses in addition to their regular vacuum system, that makes the spinning vacuum necessary for the spinning process available. The suction traverses, that extend along the work stations, are arranged in the area of the upper part of the spinning machine and comprise a rotary slider valve at each work station to which valve the service unit docks with a trunk-like device if service is required.